Band narrowing laser

Abstract

A band narrowing laser having a band narrowing module which narrows by a band narrowing element a band of the laser beam generated from a laser medium, in which wavefront correction means ( 10 ) that corrects the wavefront of an incident laser beam and and projects the corrected beam is intalled in the band narrowing module ( 6 ) to produce a laser beam with a narrow and stable spectral line width.

What is claimed is:  
     
       1. A band narrowing laser including a band narrowing module having a beam expander and an angle-dispersing wavelength-selecting element, for band-narrowing a laser beam generated from a laser medium by the band narrowing module, characterized in that: 
       the band narrowing module comprises wavefront changing means for changing wavefront of incident laser beam and outputting the laser beam and regulating means for regulating a degree of wavefront change made by the wavefront changing means, disposed between the laser medium and the angle-dispersing wavelength-selecting element.  
     
     
       2. The band narrowing laser according to  claim 1 , characterized in that the wavefront changing means comprises: 
       a first optical element having a convex lens function; and  
       a second optical element having a concave lens function, and  
       the regulating means comprises:  
       distance regulating means for regulating a relative distance between the first and second optical elements.  
     
     
       3. The band narrowing laser according to  claim 1 , characterized in that the wavefront changing means comprises: 
       a reflecting optical element for reflecting incident laser beam; and  
       the regulating means comprises:  
       a concave-convex regulation means for pending reflecting surface of the reflecting optical element to regulate concave-convex date thereof.  
     
     
       4. The band narrowing laser according to  claim 3 , characterized in that the concave-convex regulating means comprises: 
       a plurality of support members for supporting the reflecting optical element, at least a portion or portions of the support members being configured so that they can expand and contract freely;  
       a securing member or members that secure the ends of the plurality of support members; and  
       expansion-contraction control means for controlling expansion and contraction of the freely expanding and contracting support members so that a preset, prescribed bending is imparted to the reflecting optical element.  
     
     
       5. The band narrowing laser according to  claim 4 , characterized in that the freely expanding and contracting support members are configured by piezoelectric elements. 
     
     
       6. The band narrowing laser according to  claim 1 , further comprising monitor means for monitoring the laser beam generated from the laser medium, and control means for controlling the regulating means based on a value monitored by the monitor means. 
     
     
       7. The band narrowing laser according to  claim 6 , characterized in that: the monitor means has spectral line width detection means for d detecting spectral line width of output laser beams; and the control means controls the regulating means based on values detected by the spectral line width detection means. 
     
     
       8. A band narrowing laser including a band narrowing module for band-narrowing a laser beam generated from a laser medium and wavefront correction means for correcting wavefront of an incident laser beam and outputting the laser beam, disposed inside the module, characterized in that: 
       the wavefront correction means comprises:  
       a transmissive optical element for transmitting the incident laser beam;  
       a plurality of heating-cooling devices dispose outside the services of the transmissive optical element; and  
       temperature control means for temperature-controlling the heating-cooling devices and regulating temperature distribution in the transmissive optical element so as to affect a pre-set, prescribed refractive index distribution or correct the wavefront of the incident laser beam.  
     
     
       9. A band narrowing laser including a band narrowing module having a band narrowing element for band-narrowing a laser beam generated from a laser medium, and wavefront correction means for correcting wavefront of an incident laser beam and outputting the laser beam, disposed inside the band narrowing module, characterized in that: 
       the wavefront correction means comprise:  
       a reflecting optical element for reflecting the incident laser beam, configured of a material exhibiting a prescribed coefficient of thermal expansion; and  
       concave-convex regulating means for bending reflecting surface of the reflecting optical element to regulate concave-convex state thereof, and  
       the concave-convex regulating means comprises:  
       one or a plurality of heating-cooling devices disposed on a back side of the reflecting optical element; and  
       temperature regulating means for controlling the one or plurality of heating-cooling devices so that preset, prescribed bending is imparted to the reflecting optical element.  
     
     
       10. A band narrowing laser including a band narrowing module having a band narrowing element for band-narrowing a laser beam generated from a laser medium; wavefront correction means for correcting wavefront of an incident laser beam and outputting the laser beam, disposed inside the band narrowing module, characterized in that the band narrowing laser comprises: 
       monitor means for monitoring the laser beam generated from the laser medium; and  
       control means for controlling wavefront corrections made by the wavefront correction means, based on a value monitored by the monitor means,  
       the monitor means comprises shot count detection means for detecting number of output laser beam shots; and  
       the control means controls the wavefront corrections made by the wavefront correction means, based on values detected by the shot count detection means.  
     
     
       11. A band narrowing laser including a band narrowing module having a band narrowing element for band-narrowing a laser beam generated from a laser medium; wavefront correction means for correcting, wavefront of an incident laser beam and outputting the laser beam, disposed inside the band narrowing module, characterized in that the band narrowing laser comprises: 
       monitor means for monitoring the laser beam generated from the laser medium; and  
       control means for controlling wavefront corrections made by the wavefront correction means, based on a value monitored by the monitor means,  
       the monitor means comprises:  
       spectral line width detection means for detecting spectral line width of the output laser beam; and  
       output energy detection means for detecting an output energy value of the output laser beam; and  
       the control means comprises:  
       division means for dividing the energy value detected by the output energy detection means by the spectral line width detected by the spectral line width detection means; and  
       wavefront correction control means for controlling wavefront corrections made by the wavefront correction means so that a quotient value of the division means is maximized.  
     
     
       12. A band narrowing laser including a band narrowing module having a band narrowing element for band-narrowing a laser beam generated from a laser medium; wavefront correction means for correcting wavefront of an incident laser beam and outputting the laser beam, disposed inside the band narrowing module, characterized in that the band narrowing laser comprises: 
       monitor means for monitoring the laser beam generated from the laser medium; and  
       control means for controlling wavefront corrections made by the wavefront correction means, based on values monitored by the monitor means,  
       the monitor means comprises output energy detection means for detecting an output energy value of the output laser beam; and  
       the control means comprises wavefront correction control means for controlling wavefront corrections made by the wavefront correction means so that the energy value detected by the output energy detection means is maximized.